Arrangement for heating the cylinders of diesel engines



Nav.- 21, 1967 G. HAAG 3,353,529

ARRAGEMENT FOR HEATING THE CYLINDERS OF DIESEL ENGINES Filed Sept. 8, 1965 United States Patent Oflice 3,353,520 ARRANGEMENT FOR HEATING THE CYLINDERS F DIESEL ENGENES Gustav Haag, Stuttgart-Schonherg, Germany, assigner to Robert Bosch GmbH, Stuttgart, Germany Filed Sept. 8, 11965, Ser.. No. 485,860 Claims priority, appiication Germany, Sept. 11, 1954, B 78,477 13 Claims. (Cl. 12S-27) ABSTRACT 0F THE DSCLOSURE The air admitting pipe of the diesel engine accommodates a glow plug which heats and atomizes fuel delivered by a supply conduit which contains a solenoid valve. The electric circuit of the heating unit in the glow plug can be completed by a master switch which can also complete the circuit of an impulse generator serving to intermittently open and close the Valve. An interrupter switch closes the valve when the speed of the engine rises to a predetermined value. The glow plug heats the fuel to a temperature which is high enough to insure automatic ignition on entry into the air admitting pipe whereby the resulting llames penetrate into and heat the cylinders of the diesel engine.

The present invention relates to diesel engines in general, and more particularly to diesel engines of the type which may be used in automotive vehicles. Still more particularly, the invention relates to an improved arrangement for igniting fuel in the suction pipe of a diesel engine.

It is already known to provide a diesel engine with a so-called glow plug to assist is starting. The glow plug evaporates liquid fuel and admits it into the suction pipe so that such fuel forms flash flames which areentrained toward and heat the cylinder of the engine. A serious drawback of heretofore known glow plugs is that the generation of flames results in withdrawal of too much oxygen from the air that flows into the engine. ln other words, and in order to raise the temperature to that which is necessary for starting of the engine, a suction pipe which is combined with a conventional glow plug feeds a gaseous current which contains a relatively small percentage of oxygen. Consequently, proper metering must be renewed in each practical instance but invariably remains dependent on operating conditions. For example, and assuming that the operator forgets to turn olf the glow plug after starting, an engine which starts properly might not be able to run at maximum r.p.m. if the admission of fuel by the glow plug is excessive because the engine does not receive a sufhcient amount of oxygen for operation at full rotational speed. Experiments to regulate the feed of fuel by compressed air and to admit oxygen to such com-pressed air are known but have proven to be ineffective because the use of compressed air entails additional expenses and cannot be resorted to in all types of diesel engines.

Accordingly, it is an important object of the present invention to provide a diesel engine which is equipped with a glow plug and wherein the admission of fuel to the glow plug is regulated in such a way that it is terminated automatically in response to a certain operating condition of the engine.

Another object of the invention is to provide an engine of the just outlined characteristics wherein the delivery of fuel to the glow plug is terminated in response to a predetermined rotational speed which is preferably less than the maximum r.p.m. so that the suction pipe can 3353,52@ Patented Nov. 2l, 1967 deliver sufficient amounts of oxygen for operation at maximum rpm.

A further object of the instant invention is to provide a novel electric circuit which controls the heating of fuel in the glow plug and the delivery of fuel into the glow plug.

An additional object of the invention is to provide a control device which may be used in the electric circuit of the fuel flow control valve to terminate the delivery of fuel to the glow plug when the engine or its parts assume a certain operating condition.

Still another object of the invention is to provide a glow plug and a fuel fiow controlling valve therefor which may be readily installed in many presently known diesel engines without necessitating appreciable alterations in the construction of such engines.

A further object of the invention is to provide an engine of the above outlined characteristics wherein the delivery of fuel to the glow plug is controlled in such a way that the glow plug may produce flames which will heat the engine to requisite temperature but the suction pipe can still deliver maximum quantities of oxygen to one or more cylinders of the engine.

Still another object of the invention is to provide a diesel engine, particularly for use in automotive vehicles,

wherein the operation of the glow plug cannot interfere with (or affects only negligibly) the admission of oxygen to the cylinders.

Briefly stated, one feature of the present invention resides in the provision, in a diesel engine which is particularly suited for use in automotive vehicles, of an air conveying pipe, a glow plug comprising electric heating means and nozzle means positioned to exchange heat with the heating means and discharging into the pipe,

conduit means for supplying fuel to the nozzle means so that such fuel is heated and produces dames on entry into the current of air in the pipe, normally closed electric valve means provided in the conduit means, a source of electrical energy, switch means arranged to be closed and to thereby connect the heating means in circuit with the source to heat the nozzle means, and control means for regulating the opening of the valve means in response to completion of the circuit for the heating means.

The control means may comprise an interrupter switch which opens the circuit of the valve means when the rpm. of the engine increases to a predetermined value. The control means may also comprise a blinker-type switch which opens and closes the valve means at regular or irregular intervals so that fuel admitted into the pipe withdraws from the air current some oxygen when the valve means is open but the pipe can feed a maximum amount of oxygen when the valve means is closed. The interrupter switch may be used with or without the blinker-type switch, or vice versa.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved flame generating device itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of a specific embodiment with reference to the accompanying drawings, in which:

FIG. l is a diagrammatic view of a portion of a diesel engine which embodies the present invention; and

FIG. 2 is an enlarged section through a glow plug which forms part of the structure shown in FIG. l.

Referring iirst to FIG. 1, there is shown a portion of a diesel engine including a tank T which contains a supply of fuel, a supply pump FP which conveys a stream of fuel from the tank T and through a first feed line l5 containing a filter F and a fuel injection pump EP. A return line 16 conveys fuel back to the tank T when the fuel pump FP is idle, and a second feed line 17 delivers fuel from the filter F on to a reservoir B whose outlet is connected with the intake end of a supply conduit containing a solenoid valve V. The supply conduit 5 discharges into a so-called glow plug FG which extends in part into an air admitting pipe 7 leading to engine 19. The direction in which a current of air may be drawn through the pipe 7 is indicated by the arrows 8. The reservoir B is at least partially filled with fuel before the engine is started so that the glow plug FG can receive fuel as soon as the valve V opens.

The electric circuit of the engine includes a main switch or master switch S which is closed when the operator desires to start the glow plug FG. The circuit of the glow plug further includes a source 18 of electrical energy and is completed when the switch S is closed so that the current flows through an electric heating element 4 of the glow plug FG (see FIG. 2) and heats the same to thereby exchange heat with a tubular nozzle 6. The nozzle 6 is provided with orifices or perforations 6 and is connected with the discharge end of the supply conduit 5 so as to receive fuel in response to opening of the valve V. It will be noted that the nozzle 6 and the heating element 4 extend substantially radially through the wall of and into the interior of the air admitting pipe 7. The heating element 4 may consist of a length of convoluted resistance wire which is heated to incandescence when the switch S is closed and the circuit of the glow plug is completed. The electrical connection bet-Ween one end of the heating element 4 and one contact of the switch S comprises a conductor 1. The switch S and the heating element 4 are connected in series so that the glow plug FG is on as long as the switch is closed.

The switch S is further connected in circuit with an impulse generator IG, and this impulse generator is connected in series with the solenoid valve V. The valve opens when the switch S is closed and when the impulse generator IG allows electric current to fiow therethrough. The impulse generator IG is of known design and serves to open and close the valve V (via conductor 3) at a predetermined frequency whereby the valve admits jets of fuel through the supply conduit 5 and into the glow plug FG. Such fuel is heated by the nozzle 6 to evaporation temperature and issues through orifices 6 to be ignited on admixture to air which flows in the suction pipe 7 in a direction as indicated by the arrows t8. The resulting flash fiames 9 are drawn into the cylinder of the diesel engine.

In order to bring the operation of the glow plug FG in proper relationship with the r.p.m. of the engine, the system shown in FIG. 1 preferably comprises an interrupter switch DS (shown by broken lines) which is connected between the conductors 2 and 3, as at 10, and which is actuated, as indicated by the dash-dotted line 20, by the engine 19 so that its operation depends on the r.p.m. of the engine. The function of the switch DS is to throttle the impulse generator IG in response to increasing r.p.rr1. and to turn off the impulse generator when the rpm. reaches a predetermined value. In other words, when the r.p.m. of the diesel engine rises to a predetermined value, the switch DS opens the circuit of the solenoid valve V. If, after the engine is accelerated to such predetermined r.p.m., the operator forgets to open the main switch S, the glow plug FG cannot receive fuel from the reservoir B and its heating element 4 merely heats air which is being sucked through the pipe 7.

The impulse generator IG may be a blinker-type switch of the type similar to those used in directional signal devices of automobiles. Its operation will be readily understood by looking at FIG. 1. A very important advantage of this impulse generator is that it opens the valve V intermittently, preferably at rapidly recurring regular intervals, so that the fuel which is discharged from the nozzle 6 will withdraw from the pipe 7 a certain amount of oxygen only at such times when the valve V is open. Thus, the pipe 7 may convey a maximum amount of l oxygen past the glow plug FG when the valve V is closed. In addition, such intermittent admission of fuel to the nozzle 6 results in generation of very strong jets of evaporated fuel which produces highly satisfactory ames capable of assisting in rapid heating and starting of the engine.

The impulse generator IG may be a flasher switch, f.i. according to the U.S. Patent 2,700,083 and the interrupter with DS depending on the r.p.m. may be a well known centrifugal switch or a relay controlled by the voltage of an electric current generator.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications -without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is:

1. An arrangement for heating air which is sucked into a diesel engine, comprising an air conveying pipe; a glow plug comprising electric heating means and nozzle means positioned to exchange heat with said heating means and discharging into said pipe; conduit means for supplying fuel to said nozzle means so that such fuel is heated and produces flames on entry into said pipe; normally closed electric valve means provided in said conduit means; a source of electrical energy; switch means arranged to be closed and to thereby connect said heating heans in circuit with said source; and control means including means for intermittently opening and closing said valve means in response to completion of said circuit so as to produce intermittent flames.

2. An arrangement as defined in claim 1, wherein the means for intermittently opening said valve means comprises an impulse generator.

3. An arrangement as defined in claim 2, wherein said control means further comprises second switch means arranged to open said circuit in dependency on the operating condition of the engine.

4. An arrangement as defined in claim 3, wherein said second switch means is constituted by a speed-responsive switch which opens said circuit in response to acceleration of the engine to a predetermined speed.

5. An arrangement as defined in claim 4, `wherein said impulse generator comprises a switch arranged to open and close said valve means at a predetermined frequency.

6. An arrangement as defined in claim v1, further comprising a fuel tank, a reservoir connected with said conduit means, a line connecting said tank with said reservoir, and a fuel supply pump in said line for -delivering fuel from the tank to said reservoir, said valve means being constituted by a solenoid valve and said source of electrical energy being connected in separate circuits with said solenoid valve and said heating means, said switch means comprising a main switch common to said circuits and arranged to complete the circuit of said heating means upon closing thereof, said control means being provided 1n the circuit of said solenoid valve.

7. An arrangement as set forth in claim 6, wherein said main switch is connected in series with said source, with said heating means, with said control means and with said valve.

8. An arrangement as set forth in claim 6, wherein said pipe is the intake manifold of the engine and wherein said heating means comprises a resistance wire provided in the interior of said nozzle, said nozzle having orifices located in said pipe for discharging heated fuel into the current of air -that tiows through said pipe.

9. An arrangement as set forth in claim 6, wherein the means for intermittently opening said valve means comprises a blinker-type switch.

10. An arrangement as set forth in claim 9, wherein said control means further comprises an interrupter switch connected in series with said blinker-type switch and ar- 5 ranged to open the circuit of said valve in response to a predetermined increase in r.p.m. of the engine.

11. An arrangement as set forth in claim 6, wherein said control means further comprises an interrupter switch arranged to open the circuit of said Valve in response to a 10 predetermined r.p.m. ofthe engine.

12. An arrangement for heating air which is sucked into a diesel engine, comprising an air conveying pipe; a glow plug comprising nozzle means discharging into said pipe and means for heating said nozzle means; conduit means for supplying fuel to said nozzle means; valve means provided in said conduit means; and means for intermittently opening and closing said valve means so that, in response to each opening thereof, said valve means intermittently admits fuel to said nozzle means and such fuel is heated,

prior to discharge into said pipe, to a temperature which suces to bring about ignition in response to mixing 'with air so as to produce intermittent ames in said conduit means.

13. An arrangement as set forth in claim 12, further comprising means for maintaining said valve means in closed position in response to a predetermined operating condition of the engine.

References Cited UNITED STATES PATENTS 2,229,714 1/ 1941 Wirrer 123--27 2,398,094 4/ 1946 Heymann 123--122 3,020,903 2/'1'962 Kloss 123--179 FOREIGN PATENTS 586,269 11/ 1959 Canada.

LAURENCE M. GOODRIDGE, Primary Examiner. 

1. AN ARRANGEMENT FOR HEATING AIR WHICH IS SUCKED INTO A DIESEL ENGINE, COMPRISING AN AIR CONVEYING PIPE; A GLOW PLUG COMPRISING ELECTRIC HEATING MEANS AND NOZZLE MEANS POSITIONED TO EXCHANGE HEAT WITH SAID HEATING MEANS AND DISCHARGING INTO SAID PIPE; CONDUIT MEANS FOR SUPPLYING FUEL TO SAID NOZZLE MEANS SO THAT SUCH FUEL IS HEATED AND PRODUCES FLAMES ON ENTRY INTO SAID PIPE; NORMALLY CLOSED ELECTRIC VALVE MEANS PROVIDED IN SAID CONDUIT MEANS; A SOURCE OF ELECTRICAL ENERGY; SWITCH MEANS ARRANGED TO BE CLOSED AND TO THEREBY CONNECT SAID HEATING HEANS IN CIRCUIT WITH SAID SOURCE; AND CONTROL MEANS INCLUDING MEANS FOR INTERMITTENTLY OPENING AND CLOSING SAID VALVE MEANS IN RESPONSE TO COMPLETION OF SAID CIRCUIT SO AS TO PRODUCE INTERMITTENT FLAMES. 